The rest of his friends would probably gather around him, offering support and trying to cheer him up. They'd bring him water or whatever they thought might make him feel better. They'd also share stories to distract him from the pain, like the time they had an adventure together and overcame a difficult obstacle.
Well, Boruto could be very inspired. Naruto's past is full of struggles, from not having parents around to being constantly underestimated. When Boruto discovers this in the fanfiction, he might realize that his own problems are not as big as he thought. He could be motivated to work harder and not take for granted the things he has, seeing how much Naruto had to fight for everything.
Boruto and his friends would face many challenges in adapting to the past. They are used to modern conveniences like instant communication devices. In the past, they'd have to rely on messengers or their own physical abilities to communicate. Also, they'd need to adjust to the different fighting styles and weapons. The ninjutsu they know might be too advanced for the past, so they'd have to be careful not to show off too much and draw unwanted attention. They might also struggle with the food and living conditions which were much more primitive compared to their time.
Boruto might be in awe. He has always known his father as the Hokage, a powerful and respected figure. Seeing Naruto's past full of struggles, loneliness, and determination would make him realize how far his father has come. It could also make Boruto more empathetic towards Naruto and perhaps inspire him to be more like his father in some ways.
Naruto would be devastated. He might blame himself for not being able to protect his son. Sasuke would be angry and would likely go on a hunt for the perpetrator. His friends like Sarada and Mitsuki would be heartbroken. Sarada might vow to become stronger to prevent such a tragedy from happening again.
Boruto's reaction would be complex. He'd be heartbroken, for sure. He might start to question his own worth and purpose. But over time, he'd realize that he has to carry on Naruto's legacy. He'd become more serious and focused. He'd also become more empathetic towards others, understanding the weight of sacrifice. He might even start to study Naruto's techniques and leadership style more closely, trying to emulate the things that made Naruto such a great Hokage and hero.
Harry would probably be overjoyed at first. After all, he has always longed for his parents. He might start to look for ways to make it happen, like searching for magic spells or ancient artifacts that could bring his parents back.
At the start, Harry would be stunned. His whole life has been built on the idea of his parents being heroes. When he realizes they betrayed him, he would be heartbroken. He might go on a journey to find out the real motives behind their actions. Along the way, he could become bitter and vengeful. However, he might also find some inner strength and decide to rise above the betrayal. He could use it as a motivation to break free from the shadows of his parents and create his own path, but not without a great deal of emotional turmoil first.